Cold drawing of nylon filaments

ABSTRACT

An apparatus for cold-draw stretching at least one tow of nylon filaments including a frame, first and second pairs of spaced rollers mounted for rotation transversely of said frame, said second pair of rollers being spaced from said first pair of rollers in a direction longitudinally of said frame, said rollers defining a path in which a tow of said yarn passes around said first pair of rollers in a plurality of loops and around said second pair of rollers in a plurality of loops, said loops being spaced axially along said rollers such that said tow passes to said first pair of rollers and leaves said second pair of rollers adjacent one end thereof and passes between said pair of rollers adjacent the other end thereof, said second pair of rollers being adapted to rotate at a peripheral speed higher than said first pair of rollers whereby said tow is stretched during its passage between said pairs of rollers, the axes of rotation of the rollers in each of said first and second pairs of rollers being horizontally inclined such that the point of intersection of the axes of rotation of said first pair of rollers is axially remote from the point of intersection of the axes of rotation of said second pair of rollers whereby the tow may be passed to said first and second pair of rollers at a point remote from said point of axial intersection and removed therefrom at a point adjacent said point of axial intersection with reduced bunching of said loops around said first and second pairs of rollers.

United States Patent {72] inventors Donald [.MacKey 33 Forest Road; Terance Donald MacKey, R. R. 4. Galt, Ontario, Canada [21 J Appl. No. 787,333

[22] Filed Dec. 27, 1968 [45] Patented May25, 1971 [54] COLD DRAWING OF NYLON FILAMENTS Primary Examiner-Louis K. Rimrodt AttorneyCushman, Darby & Cushman ABSTRACT: An apparatus for cold-draw stretching at least one tow of nylon filaments including a frame, first and second pairs of spaced rollers mounted for rotation transversely of said frame, said second pair of rollers being spaced from said first pair of rollers in a direction longitudinally of said frame, said rollers defining a path in which a tow of said yarn passes around said first pair of rollers in a plurality of loops and around said second pair of rollers in a plurality of loops, said loops being spaced axially along said rollers such that said tow passes to said first pair of rollers and leaves said second pair of rollers adjacent one end thereof and passes between said pair of rollers adjacent the other end thereof, said second pair of rollers being adapted to rotate at a peripheral speed higher than said first pair of rollers whereby said tow is stretched during its passage between said pairs of rollers, the axes of rotation of the rollers in each of said first and second pairs of rollers being horizontally inclined such that the point of intersection of the axes of rotation of said first pair of rollers is axially remote from the point of intersection of the axes of rotation of said second pair of rollers whereby the tow may be passed to said first and second pair of rollers at a point remote from said point of axial intersection and removed therefrom at a point adjacent said point of axial intersection with reduced bunching of said loops around said first and second pairs of rollers.

PATENTEI] m5 197i SHEET 1 [IF 2 Ame/W570 SHEET 2 OF 2 PATENTED W25 |97| FIGB COLD DRAWING OF NYLON FILAMENTS The present invention relates to the cold draw stretching of undrawn nylon filaments to effect orientation thereof whereby to increase the strength of said filaments. In particular, the present invention provides an apparatus for use in effecting said stretching of the undrawn nylon filament in the form of one or more tows in a smooth and continuous manner without undesirable bunching or buildup of the loops of the tows on the rollers of the apparatus.

It is known that the cold-draw stretching of nylon filaments orients the filaments and thus substantially increases their strength. The stretching of the nylon filaments has heretofore been effected by passing the nylon filament in the form of a large tow which is made up of at least 50 similar tows. Each of these smaller tows have anywhere from 840 up to 3,000 filaments or in the form of a yarn, i.e. a twisted tow around a first roller in a plurality of axially spaced loops the second roller rotating at a greater peripheral speed that the first roller whereby the nylon filaments in the tow or yarn are stretched during the passage of the tow or yarn between the rollers. However, in the operation of such apparatus there has been a strong tendency for the loops of the tow passing around each roller in generally axially spaced relationship to bunch or buildup on a relatively small portion of the roller which substantially hinders the passage of the tow through the rollers and this bunching or building up of loops of the tow on the rollers is further accentuated when a band formed from a plurality of tows is passed through the apparatus such that each of the loops on the roller is formed from a plurality of tows.

The present invention provides an apparatus for cold-draw stretching of at least one and preferably a plurality of tows of nylon filament which substantially reduces and desirably completely eliminates the tendency of the loops on the rollers to bunch or build up and in particular allows for the simultaneous and smooth passage of a plurality of multifilament tows therethrough for stretching of the filaments.

It has now been found according to the present invention that by providing for the loops to pass around a pair of spaced rollers instead of a single roller and by disposing the rollers of each pair such that the axes of rotation thereof are horizontally inclined with the points of intersection of the axes of rotation of each pair of rollers axially remote from each other, a tow or a plurality of tows passed to one of said pairs of rollers progresses smoothly in a plurality of unbunched substantially uniform loops axially spaced across said pairs of rollers, passes to the other of said pairs of rollers at the point of intersection of the axes of rotation of said pair of rollers, progresses smoothly in a plurality of unbunched substantially uniform loops across the other pair of rollers and is removed from said other pair of rollers at the point of intersection of the axes of rotation thereof.

According to the present invention therefore there is provided an apparatus for cold-draw stretching at least one tow of nylon filament, said apparatus including a frame, first and second pairs of spaced rollers mounted for rotation transversely of said frame, said second pair of rollers being spaced from said first pair of rollers in a direction longitudinally of said frame, said rollers defining a path in which a tow of said filaments passes around said first pair of rollers in a plurality of axially spaced loops and around said second pair of rollers in a plurality of axially spaced loops such that said tow passes to said first pair of rollers and leaves said second pair of rollers adjacent one end thereof and passes between said pair of rollers adjacent the other end thereof, said second pair of rollers being adapted to rotate at a peripheral speed higher than that of said first pair of rollers whereby said tow is stretched during passage between said pair of rollers, the axes of rotation of the rollers in each of said first and second pair of rollers being horizontally inclined such that the point of intersection of the axes of rotation of said first pair of rollers is axially remote from the point of intersection of the axes of rotation of said second pair of rollers whereby the tow may be passed to said first and second pair of rollers at a point remote from the point of axial intersection and removed therefrom at a point adjacent said point of axialintersection with reduced bunching of said loops during their passage around said first and second pairs of rollers.

The rollers of each pair are preferably vertically spaced and more preferably vertically parallel. In a preferred embodiment of the present invention the upper rollers of each pair are horizontally parallel and the axes of rotation of the lower rollers are horizontally inclined thereto. With such arrangement of the rollers, the tow is preferably adapted to be passed to and leave the upper rollers of each pair of rollers during its passage through the apparatus.

It is essential to effect stretching of the tow of nylon filament that the peripheral speed of the second pair of rollers is faster than the peripheral speed of the first pair of rollers and in a preferred embodiment of the present invention, the first and second pair of rollers are identical the second pair of rollers being adapted to be rotated at a speed faster than the first pair of rollers.

In order that the tow of nylon filaments may be continuously fed to the first pair of rollers at a point remote from the point of intersection of the axes of rotation of said roller, and as such counteract the natural pull, due to the inclination of the axes of rotation of the rollers, of the tow axially of said rollers, a guiding means such as a lead-in gate is provided suitably attached to said frame. Further, in order to provide the correct tension in the tow fed to the first pair of rollers there are provided tensioning means suitably in the form of pretensioning bars adapted to tension the tow prior to its passage to said first pair of rollers. The tensioning means also desirably includes a tensioning roller suitably a rubber roller in contact with the upper roll of said first pair of rollers. The tensioning bars and the tensioning roller flatten the tow such that it contacts the first roller in the form of a flat band and the lead-in gate besides locating the band on the upper roller also limits the width of the fiat band entering onto the roller.

During its passage around the first and second pairs of rollers, there is some slippage and this slippage is facilitated by the presence of water on the tow as it contacts the upper of said first pair of rollers. The presence of water in addition to providing some slippage also cools the tow which tends to be heated up during its passage through the rollers due to the heat generated from the stretching and frictional sources in the apparatus. Suitably therefore means are provided for spraying water onto the tow as it contacts the upper of said first pair of rollers.

The present invention will be further illustrated by way of the accompanying drawings in which:

FIG. 1 is a side elevation of an apparatus for cold-draw stretching of nylon filaments according to one embodiment of the present invention;

FIG. 2 is a detailed perspective view of the input end of the apparatus of FIG. 1; and

FIG. 3 is a diagrammatic representation of the relevant disposition of the rollers to each other in the apparatus of FIG. 1.

Referring to the drawings, the apparatus comprises a first pair of rollers including an upper roller 1 and a lower roller 2 mounted for rotation on spindles 3 and 4 respectively in bushings 5 and 6 respectively, transversely of a frame 7. A second pair of rollers including an upper roller 8 and a lower roller 9 are also mounted for rotation on spindles 10 and 11 respectively in bushings 12 and 13 respectively, transversely on frame 7. The bottom rollers 2 and 9 are idler rollers whereas the upper rollers 1 and 8 are driven rollers from a motor 14 via chain wheels 15 and 16 respectively and chains 17 and 18 respectively. The chain wheel 15 is smaller'than the chain wheel 16 such that the upper roller 8 rotates at a faster speed than the upper roller 1, all the rollers 1, 2, 8 and 9 being identical and suitably made of stainless steel. In a typical embodiment the roller 1 is adapted to rotate at a speed of 27 r.p.m. and the roller 8 is adapted to rotate at a speed of r.p.m. giving a draw ratio of 3.52.

As will be seen from the drawings and particularly from FIG. 3, the lower roll 2 is horizontally inclined to the upper roller 1 and the lower roller 9 is horizontally inclined to the upper roller 8 with the crossover point 19 between the first axially in a plurality of spaced loops 23 for example eleven.

such loops around the rollers 1 and 2 to the crossover point 19 from whence the band 21 passes to the upper roller 8 of the second pair of rollers at a point remote from the crossover point and progresses axially in a plurality of spaced loops 24 suitably again eleven such loops around the rollers 8 and 9 to the crossover point 20 from whence the band 21 is taken off from the upper roller 8.

The band 21 is stretched during its passage between the upper rollers l and 8 due to the faster speed of rotation of the second pair of rollers giving for example the aforesaid draw ratio as 3.52 and the progression of the loops 23 and 24 to the crossover points 19 and 20 respectively is automatically uniform, the loops 23 and 24 being spaced and uniform with no significant bunching. From the crossover point 20 the band 21 of stretched nylon filament is taken from the upper roller 8 and passed over steel bar 25 into crimper rolls 26 driven from the motor 14 via chain wheel 27 and chain 28. The crimper rolls are suitably driven at a rate of about 203 rpm, when the first pair of rolls rotate at a speed of 27 r.p.m. and the second pair of rolls rotate at a speed of 95 r.p.m. The band 21 of crimped and drawn nylon filaments is then passed into a crimper box 29.

The nylon filaments fed to the upper roll 1 are withdrawn from a stack of creels (not shown) and the filaments form a pair of tows 30 passing via a pair of sleeve guides 31 and pretensioning bars 32 to the roll 1 through the guide 22. The pretensioning bars 32 provide the required tension in the fila ments and at the same time flatten the tows of filaments 31 into the band 21, the width of which is determined by the dimensions of the leading guide 22. As the band 21 passes to the upper roll 1 of the first pair of rollers it is contacted by a tensioning roller 33 carried on a resiliently flexible arm 34 attached to the frame 7 and is impregnated with water dripping from a supply conduit 35. The tensioning roller 33 which is suitably made of rubber serves to provide a fine adjustment to the tension in the nylon filaments and the water serves to lubricate and cool the nylon filaments during their passage around the first and second pair of rollers.

We claim:

1. An apparatus for cold-draw stretching at least one tow of nylon filaments including a frame, first and second pairs of vertically spaced rollers mounted for rotation transversely of said frame, said second pair of rollers being spaced from said first pair of rollers in a direction longitudinally of said frame, said rollers defining a path in which a tow of said yarn passes around said first pair of rollers in a plurality of loops and around said second pair of rollers in a plurality of loops, said loops being spaced axially along said rollers such that said tow passes to said first pair of rollers and leaves said second pair of rollers adjacent one end thereof and passes between said pair of rollers adjacent the other end thereof, said second pair of rollers being adapted to rotate at a peripheral speed higher than said first pair of rollers whereby said tow is stretched during its passage between said pairs of rollers, the axes of rotation of the rollers in each of said first and second pairs of rollers being vertically parallel and horizontally inclined such that the point of intersection of the axes of rotation of said first pair of rollers is axially remote from the point of intersection ofthe axes of rotation of said second pair of rollers whereby the tow may be passed to said first and second pairs of rollers at a point remote from said point of axial intersection and removed therefrom at a point ad acent said point of axial tntersection with reduced bunching of said loops around said first and second pairs of rollers.

2. An apparatus as claimed in claim 1 in which the axes of rotation of the upper rollers of each pair are horizontally parallel and the axes of rotation of the lower rollers are horizontally inclined thereto.

3. An apparatus as claimed in claim 1 in which the tow is adapted to be passed to and leave from the upper roller of each pair of rollers.

4. An apparatus as claimed in claim 1 in which the first and second pair of rollers are identical and the second pair of rollers are adapted to be rotated at a speed faster than the first pair of rollers.

5. An apparatus as claimed in claim 1 in which guide means are provided for guiding the tow onto said first pair of rollers at a point remote from the point of intersection of the axes of rotation of said rollers. v

6. An apparatus as claimed in claim 1 including pretensioning bars adapted to tension the tow prior to its passage to said first pair of rollers.

7. An apparatus as claimed in claim 1 including means for spraying cooling water onto said rollers. 

2. An apparatus as claimed in claim 1 in which the axes of rotation of the upper rollers of each pair are horizontally parallel and the axes of rotation of the lower rollers are horizontally inclined thereto.
 3. An apparatus as claimed in claim 1 in which the tow is adapted to be passed to and leave from the upper roller of each pair of rollers.
 4. An apparatus as claimed in claim 1 in which the first and second pair of rollers are identical and the second pair of rollers are adapted to be rotated at a speed faster than the first pair of rollers.
 5. An apparatus as claimed in claim 1 in which guide means are provided for guiding the tow onto said first pair of rollers at a point remote from the point of intersection of the axes of rotation of said rollers.
 6. An apparatus as claimed in claim 1 including pretensioning bars adApted to tension the tow prior to its passage to said first pair of rollers.
 7. An apparatus as claimed in claim 1 including means for spraying cooling water onto said rollers. 